    Patent Document 1: Japanese Utility Model No. H06-8335    Patent Document 2: Japanese Published Patent Application No. S59-200806
Patent document 1 proposes an outer casing 100 shown in FIG. 12 uses for a control cable of a remote control of a working robot, in which a spiral tube (armor layer) 103 is constituted by arranging alternately an irregular shape wire 101 of trapezoidal cross section and an oval wire 102 of flat and about oval cross section, and a synthetic resin layer 104 is provided around the periphery of the spiral tube 103. In this outer casing 100, the thickness of the irregular shape wire is about 2 times of the thickness of the oval wire 102. The oval wire can be obtained by milling a circular metal wire.
In this outer casing 100, when it extends in a straight line, the oval wire 102 is in the mid position of the irregular shape wire 101; and when it is bended like FIG. 13, the oval wire 102 of the inside of the bending moves toward the front edge side of the irregular shape wire 101, and the oval wire 102 of the outside of the bending moves toward the root side. Hence, small bending is possible. Further, it is said that the amount of the variation of the freeplay length (the length of the inner cable being out of the outer casing) of the inner cable 107 is small, the transmission efficiency becomes better, and the operating loss is reduced because the action of the driving portion is sufficiently transmitted to the driven portion (the left column of the third page, 17th line-end line), when an inner cable 107 is inserted into the outer casing 100 to constitute a control cable 108.
The control cable 108 is a cable in which the both edges of the inner cable 107 is latched to a drive portion and a driven portion respectively, the inner cable 107 slides inside the inner hole of the outer casing 100 by pushing and pulling the drive portion, and the motion of the inner cable is transmitted to the driven portion to remote-control an equipment (the left column of the second page, line 2 to 10).
In Patent Document 2, as shown in FIG. 14, an outer casing 110 is disclosed. The outer casing 110 comprises a spiral tube constituted by thickly winding only an oval wire 102 in spiral and a synthetic resin layer 104 provided on its periphery. This outer casing 110 is used in a control cable (transmission cable), where it is combined with an inner cable. The end of the driven portion side of the inner cable is latched and the end of the drive portion side is pull-operated, and the driven portion side of the outer casing 110 is push-operated. In this case, the control cable is bended for cabling.